JP5320756B2 - Method for producing liquid crystal polyester fiber - Google Patents

Description

  The present invention relates to a method for producing a liquid crystal polyester fiber excellent in processability and strength uniformity, and relates to a method for producing a liquid crystal polyester fiber having a small total fineness, particularly a monofilament.

  Liquid crystalline polyester is a polymer consisting of rigid molecular chains, and in melt spinning, the molecular chains are highly oriented in the fiber axis direction and further solid-phase polymerized by heat treatment at high temperatures. The highest strength and elastic modulus can be obtained. Since the liquid crystal polyester fiber has a low moisture absorption property, it has applications in ropes and nets for fishery materials. In recent years, liquid crystal polyester with relatively low total fineness, such as silk woven fabrics for screen printing, sail cloths, cord reinforcements for various electrical products, protective gloves, plastic reinforcements, optical fiber tension members, and membrane base fabrics. Demand is growing.

  In order to obtain a fiber with high strength and high elastic modulus, the liquid crystalline polyester fiber needs to be subjected to a solid-state polymerization temperature at a high temperature in the vicinity of the melting point of the liquid crystalline polyester. If it is severe when unraveling, breakage occurs, and the fused part becomes a fiber defect, causing a problem that the strength is partially reduced. In order to prevent this, a method of heat-treating at a low temperature for a long time or a method of heat-treating a fiber at a low speed in a high-temperature gas without contact can be considered, but the heat treatment time is originally from several hours to several tens of hours. Therefore, it is not realistic as mass production technology.

  In order to suppress the fusion at the time of this heat treatment, Patent Document 1 proposes a method of heat treating a package wound at a winding density of 0.16 to 0.5 g / cc. As a result, a certain degree of fusion can be avoided, but the effect of fusion cannot be eliminated when processing fibers having a low total fineness. Patent Document 2 describes that the winding density at the time of solid phase polymerization of a liquid crystal polyester monofilament having a total fineness of 50 denier (55.5 dtex) or more is 0.3 g / cc or more. Although there is a description regarding efficiency, there is no description regarding fusion during solid phase polymerization.

  On the other hand, in order to avoid fusion, Patent Document 3 proposes a method in which liquid crystal polyester fibers are deposited while being shaken down on a cylindrical container, and the fibers are entangled in advance in order to improve the subsequent removal performance. Yes. However, fibers with a fine total fineness are inefficient because they spend a long time to be deposited in a cylindrical container due to air resistance.

Patent Document 4 describes a production method in which a liquid crystal polyester monofilament having a fineness is wound around a bobbin and subjected to solid phase polymerization. However, the winding density is as high as 0.57 g / cc, and it is not an industrially useful high fusion suppression technique unless it is coated with a resin.
JP-A-61-225312 (first page) JP 04-333616 A (page 4) JP 09-256240 A (first page) JP-A-11-269737 (first page)

  An object of the present invention is to provide a method for producing a liquid crystal polyester fiber having a low total fineness excellent in processability and strength uniformity without causing fusion even when solid phase polymerization is performed in the form of a fiber package. In particular, the present invention relates to a method for producing a liquid crystal polyester fiber which is a monofilament.

The above problem is formed melt spun denier than 1 dtex, the liquid crystal polyester melt spun fiber is less monofilament 100 dtex, the winding density of 0.01 g / cc or more, on a bobbin as a fiber package of less than 0.30 g / cc However, the problem can be solved by a method for producing a liquid crystal polyester fiber, characterized in that the package is heat-treated.

  The present invention can provide a liquid crystal polyester fiber having a low total fineness that is excellent in processability and strength uniformity without causing fusion even when solid phase polymerization is performed in the form of a fiber package, and has particularly excellent characteristics. The liquid crystal polyester monofilament possessed can be produced efficiently. The liquid crystal polyester fibers obtained in this way can be used for silk fabrics for screen printing, sailcloths, cord reinforcements for various electrical products, protective gloves, plastic reinforcements, optical fiber tension members, membrane base fabrics, etc. It is particularly suitable for silk fabrics for screen printing, which are free from defects caused by fusion bonding and strongly required to have uniform strength.

  Hereinafter, the manufacturing method of the liquid crystalline polyester fiber of this invention is demonstrated in detail.

  The liquid crystal polyester used in the present invention refers to a polymer that exhibits optical anisotropy (liquid crystallinity) when melted by heating. This characteristic can be confirmed, for example, by placing a sample made of liquid crystal polyester on a hot stage, heating and heating in a nitrogen atmosphere, and observing the transmitted light of the sample under polarized light.

  Examples of the liquid crystal polyester used in the present invention include a. A polymer of aromatic oxycarboxylic acid, b. Polymer of aromatic dicarboxylic acid and aromatic diol, aliphatic diol, c. and a copolymer of a and b.

  Here, examples of the aromatic oxycarboxylic acid include hydroxybenzoic acid, hydroxynaphthoic acid and the like, and alkyl, alkoxy and halogen substituted products of the above aromatic oxycarboxylic acid.

  Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, diphenyldicarboxylic acid, naphthalene dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenoxyethanedicarboxylic acid, diphenylethanedicarboxylic acid, and the like, or alkyls, alkoxys of the above aromatic dicarboxylic acids, Examples include halogen substitution products.

  Furthermore, examples of the aromatic diol include hydroquinone, resorcin, dioxydiphenyl, naphthalene diol, and the like, and alkyl, alkoxy, and halogen substituted products of the above aromatic diol. Examples of the aliphatic diol include ethylene glycol, propylene glycol, Examples include butanediol and neopentyl glycol.

  Preferable examples of the liquid crystalline polyester used in the present invention include a copolymer of a p-hydroxybenzoic acid component, a 4,4′-dihydroxybiphenyl component, a hydroquinone component, a terephthalic acid component and / or an isophthalic acid component, p- A copolymer of a hydroxybenzoic acid component and a 6-hydroxy 2-naphthoic acid component, a copolymer of a p-hydroxybenzoic acid component, a 6-hydroxy 2-naphthoic acid component, a hydroquinone component, and a terephthalic acid component , Etc.

  In the present invention, a liquid crystal polyester composed of the following structural units (I), (II), (III), (IV) and (V) is particularly preferable. In the present invention, the structural unit refers to a unit that can constitute a repeating structure in the main chain of the polymer.

  This combination results in the molecular chain having the proper crystallinity and non-linearity, ie, a melt-spinnable melting point. Therefore, the fiber has good spinning performance at the spinning temperature set between the melting point of the polymer and the thermal decomposition temperature, and a uniform fiber can be obtained in the longitudinal direction. Can be increased. Furthermore, in the present invention, it is important to combine components composed of diols that are not bulky and have high linearity like the structural units (II) and (III). By combining these components, the molecular chains in the fiber have an ordered and less disturbed structure, and the crystallinity is not excessively increased and the interaction in the direction perpendicular to the fiber axis can be maintained. Thereby, in addition to high strength and elastic modulus, excellent wear resistance is also obtained.

  Further, the structural unit (I) is preferably 40 to 85 mol%, more preferably 65 to 80 mol%, still more preferably 68 to 85 mol% with respect to the total of the structural units (I), (II) and (III). 75 mol%. By setting it as such a range, crystallinity can be made into a suitable range, high intensity | strength and elasticity modulus are obtained, and melting | fusing point also becomes the range which can be melt-spun.

  The structural unit (II) is preferably 60 to 90 mol%, more preferably 60 to 80 mol%, still more preferably 65 to 75 mol% with respect to the total of the structural units (II) and (III). . By setting it as such a range, since crystallinity does not become high too much and the interaction of a fiber axis perpendicular | vertical direction can be maintained, abrasion resistance can be improved.

  The structural unit (IV) is preferably 40 to 95 mol%, more preferably 50 to 90 mol%, still more preferably 60 to 85 mol%, based on the total of the structural units (IV) and (V). . By setting such a range, the melting point of the polymer becomes an appropriate range, and has a good spinning property at a spinning temperature set between the melting point of the polymer and the thermal decomposition temperature. Uniform fibers can be obtained.

The preferred range of each structural unit of the liquid crystalline polyester used in the present invention is as follows. The liquid crystal polyester fiber of the present invention can be suitably obtained by adjusting the composition so as to satisfy the above conditions within this range.
Structural unit (I) 45-65 mol%
Structural unit (II) 12-18 mol%
Structural unit (III) 3 to 10 mol%
Structural unit (IV) 5-20 mol%
Structural unit (V) 2-15 mol%
The melting point (Tm0) of the liquid crystalline polyester polymer used in the present invention is preferably 200 to 380 ° C., more preferably 250 to 350 ° C., further preferably 290 to 340 ° C. in order to widen the temperature range in which melt spinning is possible. It is. Tm0 is a value obtained by the method described in the examples.

  In addition to the above structural units, the liquid crystalline polyester used in the present invention includes aromatic dicarboxylic acids such as 3,3′-diphenyldicarboxylic acid and 2,2′-diphenyldicarboxylic acid, adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid. Fragrances such as aliphatic dicarboxylic acids such as hexacycloterephthalic acid, chlorohydroquinone, 4,4′-dihydroxydiphenyl sulfone, 4,4′-dihydroxydiphenyl sulfide, 4,4′-dihydroxybenzophenone, etc. A group diol and p-aminophenol may be copolymerized within a range not impairing the effects of the present invention.

  Further, other polymers can be added and used in combination as long as the effects of the present invention are not impaired. Addition, combined use means mixing two or more polymers, using one component or two or more components partially mixed in a composite spinning of two or more components, or using all of them. Say. Other polymers include polyester, vinyl polymers such as polyolefin and polystyrene, polycarbonate, polyamide, polyimide, polyphenylene sulfide, polyphenylene oxide, polysulfone, aromatic polyketone, aliphatic polyketone, semi-aromatic polyester amide, polyether ether ketone. Polymers such as fluororesin may be added, such as polyphenylene sulfide, polyether ether ketone, nylon 6, nylon 66, nylon 46, nylon 6T, nylon 9T, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, Polycyclohexanedimethanol terephthalate, polyester 99M and the like are preferable examples. In addition, when adding these polymers, it is preferable that the melting point is within the melting point ± 30 ° C. of the liquid crystalline polyester so as not to impair the spinning property, and it is added to improve the strength and elastic modulus of the obtained fiber. The amount used in combination is preferably 40% by weight or less, more preferably 5% by weight or less, and most preferably, no other polymer is added or used in combination.

  Furthermore, within the range not impairing the effects of the present invention, various metal oxides, kaolin, silica and other inorganic substances, colorants, matting agents, flame retardants, antioxidants, ultraviolet absorbers, infrared absorbers, crystal nucleating agents In addition, various additives such as a fluorescent brightening agent, a terminal group blocking agent, and a compatibilizing agent may be contained in a small amount.

  The melt viscosity of the liquid crystalline polyester used in the present invention is preferably from 1 to 100 Pa · s under the conditions of the melting point (Tm0) + 10 ° C. and the shear rate of 1000 / s, from the viewpoint of improving the spinning stability, and from 5 to 30 Pa · s. It is more preferable to increase the spinning speed.

  In melt spinning, a known method can be used for melt extrusion of liquid crystal polyester, but an extruder type extruder is preferably used in order to eliminate the ordered structure generated during polymerization. The extruded polymer is measured by a known measuring device such as a gear pump through a pipe, and after passing through a filter for removing foreign matter, is guided to a base. At this time, the temperature from the polymer pipe to the die (spinning temperature) is preferably not less than the melting point of the liquid crystal polyester and the thermal decomposition temperature, more preferably not less than the melting point of the liquid crystal polyester (Tm0) + 10 ° C. or more and 400 ° C. or less. The melting point (Tm0) of the liquid crystal polyester is more preferably 20 ° C. or higher and 370 ° C. or lower. It is also possible to independently adjust the temperature from the polymer pipe to the base. In this case, the discharge is stabilized by making the temperature of the part close to the base higher than the temperature on the upstream side.

  In order to obtain the liquid crystal polyester fiber of the present invention, it is important to optimize the spinning conditions in order to obtain a fiber having a fineness and a low fineness variation rate using the liquid crystal polyester polymer composed of the above-described structural units. The liquid crystalline polyester polymer composed of the above-mentioned structural units can be spun at a wide range of spinning temperatures because of the large temperature difference between the melting point and the thermal decomposition temperature, and has a high thermal stability at the spinning temperature. Since fluidity is high and the thinning behavior of the polymer after ejection is stable, there is little variation in fineness, which is advantageous for obtaining fibers with fineness and low fineness variation rate. However, in order to uniformly obtain fibers with a fine total fineness, it is necessary to further increase the stability during discharge and the stability of the thinning behavior. In industrial melt spinning, 1 is required to reduce energy costs and improve productivity. Since a number of base holes are perforated in one base, it is necessary to stabilize the discharge and thinning of each hole.

  In order to achieve this, it is important to reduce the diameter of the base hole and increase the land length (the length of the straight pipe portion equal to the diameter of the base hole). However, when the hole diameter is excessively small, clogging of the hole is likely to occur, so that the diameter is preferably 0.03 mm or more and 0.30 mm or less, more preferably 0.05 mm or more and 0.25 mm or less, and 0.08 mm or more and 0.20 mm. More preferred are: If the land length is excessively long, the pressure loss becomes high. Therefore, the L / D defined by the quotient obtained by dividing the land length by the hole diameter is preferably 0.5 or more and 3.0 or less, preferably 0.8 or more and 2.5 or less. Is more preferable, and 1.0 or more and 2.0 or less are more preferable. In order to maintain uniformity, the number of holes in one die is preferably 50 holes or less, more preferably 40 holes or less, and even more preferably 20 holes or less. In addition, it is preferable that the introduction hole located immediately above the die hole is a straight hole having a diameter of 5 times or more the diameter of the die hole in terms of not increasing pressure loss. It is preferable to taper the connection part between the introduction hole and the base hole in order to suppress abnormal stagnation. However, the length of the taper part should be less than twice the land length without increasing pressure loss and stabilizing the streamline. This is preferable.

  The polymer discharged from the base hole passes through a heat retaining and cooling region and solidifies, and is then taken up by a roller (godet roller) that rotates at a constant speed. If the heat-retaining region is excessively long, the yarn forming property is deteriorated, so that it is preferably up to 200 mm from the base surface, and more preferably up to 100 mm. In the heat retaining region, it is possible to increase the ambient temperature using a heating means, and the temperature range is preferably 100 ° C. or higher and 500 ° C. or lower from the viewpoint of improving the yarn forming property, and more preferably 200 ° C. or higher and 400 ° C. or lower. For the cooling, an inert gas, air, water vapor or the like can be used. However, it is preferable to use a parallel or annular air flow from the viewpoint of reducing the environmental load.

  The take-up speed is preferably 50 m / min or more, more preferably 300 m / min or more, and further preferably 500 m / min or more in order to reduce productivity and single yarn fineness. Since the liquid crystalline polyester used in the present invention has a suitable spinnability at the spinning temperature, the take-up speed can be increased. Although the upper limit is not particularly limited, the liquid crystal polyester used in the present invention is about 2000 m / min from the viewpoint of spinnability.

  The spinning draft defined by the quotient obtained by dividing the take-up speed by the discharge linear speed is preferably 1 or more and 500 or less, more preferably 5 or more and 200 or less, and more preferably 12 or more and 100 or less for the stability of yarn production. More preferably. Since the liquid crystalline polyester used in the present invention has suitable spinnability, the draft can be increased, which is advantageous for fineness.

  In melt spinning, it is preferable to add an oil agent between the cooling and solidification of the polymer and the winding to improve the handleability of the fiber. As the oil agent, known oil agents can be used, but it is more preferable to use an oil agent mainly composed of polysiloxane-based silicone oil that can withstand solid-phase polymerization at high temperatures.

  The winding can be made into a package of a form such as pirn, cheese, corn, etc. using a known winding machine, but it is preferable that the winding is a pirn winding in which the roller does not contact the surface of the package, and the traverse is a spindle traverse. preferable.

The fineness of the fiber of the present invention is 1 dtex or more and 500 dtex or less . By making the fineness in such a narrow range, there is an advantage that the thickness of the woven fabric can be reduced, and in addition, the screen woven woven fabric can have a high mesh high opening area and can improve printing accuracy . The finer the fineness, the greater the advantage, more preferably 100 dtex or less, and more preferably 50 dtex or less.

Since the fiber of the present invention is a field in which monofilaments having a filament number of 1 , particularly fineness and uniformity of strength are strongly desired, the method of the present invention can be used particularly preferably. Therefore, the most preferable example of the method of the present invention is a monofilament of 50 dtex or less, and further a monofilament of 18 dtex or less.

  Next, the fiber obtained by the melt spinning of the present invention is heat-treated. In the heat treatment, when the melting point of the melt-spun fiber is Tm1 (° C.), the maximum temperature reaches Tm 1-60 (° C.) or more. It is processing at such temperature. As a result, the solid phase polymerization of the fiber proceeds rapidly, and the strength of the fiber can be improved. It is preferable that the maximum temperature is less than Tm1 (° C.) in order to prevent fusion. In addition, since the melting point of the liquid crystal polyester fiber increases with the progress of the solid phase polymerization, the solid phase polymerization temperature can be sequentially increased. Increasing the solid-phase polymerization temperature stepwise or continuously with respect to time is more preferable because it can prevent fusion and increase the time efficiency of solid-phase polymerization. However, also in this case, it is preferable that the maximum temperature achieved in the solid phase polymerization is Tm1-60 (° C.) or higher and less than Tm1 (° C.) of the fiber after heat treatment from the viewpoint of increasing the solid phase polymerization rate and preventing fusion. .

  The heat treatment is preferably a treatment in which the heat of fusion (ΔHm2) at the endothermic peak of the fiber after the heat treatment is 2.0 times or more than the heat of fusion (ΔHm1) at the endothermic peak of the melt-spun fiber. As a result, the crystallinity of the fiber can be sufficiently increased, and a fiber having high strength and high elastic modulus can be obtained. However, if the crystallinity is excessively high, the toughness of the fiber tends to be impaired and the workability tends to deteriorate, and the preferable range of ΔHm2 is 2.0 times or more and 15.0 times or less, more preferably 2.5 times the ΔHm1. It is twice or more and 10.0 times or less. The solid-state polymerization time for this depends on the solid-state polymerization temperature, but in order to make ΔHm2 sufficiently high, it is preferably 5 hours or more at the highest temperature and more preferably 10 hours or more. preferable. The upper limit is not particularly limited, but the effect of increasing ΔHm2 saturates with time, so about 50 hours is sufficient.

  Further, the heat of fusion (ΔHm2) of the fiber after heat treatment is preferably 1.0 J / g or more, more preferably 3.0 J / g or more, and 5.0 J / g or more in order to obtain high strength and elastic modulus. Further preferred.

  In the heat treatment, from the viewpoint of equipment productivity and production efficiency, in the present invention, the liquid crystalline polyester melt-spun fiber is formed on the bobbin as a fiber package having a winding density of 0.01 g / cc or more and less than 0.30 g / cc. And is heat-treated. In addition, the present invention is applied to fibers having a total fineness of 1 dtex or more that can be handled and a total fineness of 500 dtex or less that has a large adverse effect due to fusion.

  The winding density of the fiber package at the time of solid phase polymerization is important for preventing fusion, and the winding density is set to 0.01 g / cc or more to prevent collapse, and in order to avoid fusion, winding is performed. The density is less than 0.30 g / cc. Here, the winding density is a value calculated by Wf / Vf from the occupied volume (Vf, cc) of the fiber package and the weight (Wf, g) of the fiber. The occupied volume Vf is a value obtained by actually measuring the outer dimension of the package or by taking a photograph and measuring the outer dimension on the photograph and assuming that the package is rotationally symmetric. Wf is the fineness And a value calculated from the winding length, or a value measured by a weight difference before and after winding. The lower the winding density, the weaker the adhesion between the fibers in the package and the suppression of fusion, so 0.15 g / cc or less is preferable, and if the winding density is too low, the package will collapse, and 0.03 g / cc or more. It is preferable. Therefore, a preferable range is 0.03 g / cc or more and 0.15 g / cc or less.

  When such a low winding density package is formed by winding in melt spinning, it is desirable to improve facility productivity and production efficiency. On the other hand, a package wound by melt spinning is formed by rewinding. Is preferable because the winding tension can be reduced and the winding density can be further reduced. In order to make the winding density 0.30 g / cc or less, it is important to reduce the winding tension, and the winding tension is preferably 0.10 cN / dtex or less, and more preferably 0.05 cN / dtex or less. In order to reduce the winding density, the surface of the fiber package is wound in a non-contact state or wound by melt spinning without using a contact roller or the like normally used to adjust the package shape and stabilize the winding tension. It is also effective to wind the package directly with a winder controlled in speed without using a speed control roller. In these cases, in order to adjust the package shape, a method in which the distance (free length) from the contact point between the traverse guide and the fiber to the fiber package is within 10 mm is preferably used. Furthermore, it is also effective to reduce the winding density by setting the winding speed to 500 m / min or less, particularly 300 m / min or less. On the other hand, a higher rewinding speed is advantageous for productivity, and it is preferably 50 m / min or more, particularly preferably 100 m / min or more.

  Further, in order to avoid the fusion of the end face portions and form a stable package, it is preferable to adopt a taper end winding in which both ends of the package are tapered. At this time, the taper angle is preferably 60 ° or less, and more preferably 45 ° or less. When the taper angle is small, the fiber package cannot be enlarged, and when long fibers are required, 5 ° or more is preferable, and 10 ° or more is more preferable. Further, in winding, a package excellent in handling and unwinding property can be obtained by swinging the traverse width periodically with respect to time.

  Furthermore, the number of winds is also important for package formation. The number of winds referred to here is defined by the number of spindle rotations during a half reciprocation of the traverse, and a high wind number indicates a small traverse angle. The smaller the number of winds, the smaller the contact area between the fibers, which is advantageous for avoiding fusion. However, the higher the number of winds under the conditions such as low tension and no contact roll, which are preferable winding conditions in the present invention. Twill fall off at the end face and the swelling of the package can be reduced, and the package shape is improved. From these points, the wind number is preferably 2 or more and 20 or less, more preferably 5 or more and 15 or less.

  The bobbin used to form the fiber package may be of any cylindrical shape, and when wound as a fiber package, it is attached to a winder and rotated to wind the fiber and form a package. To do. In the heat treatment, the fiber package can be processed integrally with the bobbin, but only the bobbin can be extracted from the fiber package. When the treatment is performed while being wound around the bobbin, the bobbin needs to withstand the heat treatment temperature, and is preferably made of a metal such as aluminum, brass, iron, or stainless steel. In this case, it is preferable that the bobbin has a large number of holes because the by-products of the polymerization reaction can be removed quickly and heat treatment can be performed efficiently. Further, when the bobbin is extracted from the fiber package and processed, it is preferable to attach an outer skin to the bobbin outer layer. In any case, it is preferable that a cushion material is wound around the outer layer of the bobbin, and the liquid crystalline polyester melt-spun fiber is wound thereon. The cushion material is preferably felt made of organic fiber or metal fiber, and the thickness is preferably 0.1 mm or more and 20 mm or less. The aforementioned outer skin can be substituted with the cushion material.

  The fiber weight of the fiber package may be any weight as long as the winding density falls within the range of the present invention, but is preferably 0.01 kg or more and 10 kg or less in consideration of productivity. The yarn length is preferably in the range of 10,000 m to 2 million m.

  In order to prevent fusion at the time of solid phase polymerization, it is a preferred embodiment that oil is attached to the fiber surface. The adhesion of these components may be performed between melt spinning and winding, but in order to increase the adhesion efficiency, it is performed at the time of rewinding, or a small amount is adhered by melt spinning and further added at the time of rewinding. Is preferred.

  The oil adhering method may be a guide oiling method, but in order to uniformly adhere to fibers having a fine total fineness, adhesion by a metal or ceramic kiss roll (oiling roll) is preferable. As oil component, it is better to have high heat resistance because it is not volatilized by high temperature heat treatment in solid phase polymerization, and inorganic substances such as salt, talc and smectite, siloxane compounds (dimethylpolysiloxane, diphenylpolysiloxane, methylphenylsiloxane) And mixtures thereof are preferred. Of these, siloxane compounds are particularly preferred because they have an effect on slipperiness in addition to the effect of preventing fusion under solid weight.

  These components may be solid-coated or directly coated with oil, but emulsion coating is preferred for uniform coating while optimizing the amount of coating, and water emulsion is particularly preferred from the viewpoint of safety. Therefore, it is desirable that the component is water-soluble or easily form a water emulsion, and a mixed oil agent mainly composed of a dimethylsiloxane water emulsion and a salt or water-swellable smectite added thereto is most preferable.

  The amount of oil adhering to the fiber is preferably large in order to suppress the fusion, but if it is too large, the fiber deteriorates the stickiness handling and also deteriorates the process passability in the subsequent process. 0 wt% or less is preferable, and 1.0 wt% or more and 5.0 wt% or less is particularly preferable. The amount of oil adhering to the fiber is 100 mg or more of fiber, and the weight after drying at 60 ° C. for 10 minutes is measured (W0). The fiber was subjected to ultrasonic cleaning for 20 minutes using a cleaning liquid added with 0.1 wt%, the fiber after cleaning was washed with water, and the weight after drying at 60 ° C. for 10 minutes was measured (W1), (W0-W1) ) × 100 / W1 refers to the value obtained.

  Solid-phase polymerization can be carried out in an inert gas atmosphere such as nitrogen, an oxygen-containing active gas atmosphere such as air, or under reduced pressure, but it can simplify equipment and prevent oxidation of fibers or deposits. Therefore, it is preferable to carry out in a nitrogen atmosphere. At this time, the atmosphere of the solid phase polymerization is preferably a low-humidity gas having a dew point of −40 ° C. or less.

  The package after the solid phase polymerization can be used as a product as it is, but it is preferable to increase the winding density by rewinding the package after the solid phase polymerization in order to increase the product transport efficiency. In unwinding after solid-phase polymerization, unraveling is important. In order to prevent the solid-phase polymerization package from collapsing due to unraveling, and to suppress fibrillation when peeling light fusion, the solid-phase polymerization package is rotated. It is preferable that the yarn is unwound by so-called pre-winding, in which the yarn is unwound in the direction perpendicular to the rotation axis (fiber circulation direction), and the solid-phase polymerization package is preferably rotated by positive driving rather than free rotation. .

  The liquid crystal polyester fiber obtained in the present invention is preferably a high-strength fiber having a strength of 17.0 cN / dtex or more, more preferably 20.0 cN / dtex or more, and further preferably 25.0 cN / dtex or more. The elastic modulus is preferably 600 cN / dtex, more preferably 750 cN / dtex or more, and further preferably 900 cN / dtex or more. The upper limits of the strength and elastic modulus are not particularly limited, but the upper limits that can be achieved in the present invention are a strength of about 30 cN / dtex and an elastic modulus of about 1500 cN / dtex.

  The strength variation rate of the fiber obtained in the present invention is preferably 20% or less, more preferably 15% or less, and the strength variation rate is 20% or less, so that the uniformity in the longitudinal direction is increased and the strength (strength and strength) of the fiber is increased. Since the variation of the product of the fineness is also reduced, the defect of the fiber product is reduced, and troubles such as yarn breakage in the processing process due to the low strength portion can be suppressed.

  The liquid crystalline polyester fiber of the present invention has improved wear resistance compared to conventional liquid crystalline polyester fibers while maintaining the characteristics of high strength and high elastic modulus, and is used for general industrial materials, civil engineering / building materials, and sports applications. Widely used in fields such as protective clothing, rubber reinforcing materials, electrical materials (especially as tension members), acoustic materials, and general clothing. Effective applications include screen kites, computer ribbons, printed circuit board fabrics, paper canvases, airbags, airships, dome fabrics, rider suits, fishing lines, various lines (yachts, paragliders, balloons, kites) Thread), blind cord, support cord for screen door, various cords in automobiles and airplanes, power transmission cords for electrical products and robots, etc. Especially effective applications are textiles for industrial materials, no defects caused by fusion And monofilaments used in silk woven fabrics for screen printing, which require strong uniformity of strength.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited at all by this. The various characteristics of the present invention were evaluated by the following methods.
(1) Tm0, Tm1, ΔHm1, Tm2, and ΔHm2
The DSC2920 manufactured by TA instruments is used for differential calorimetry, and the endothermic peak temperature of the melt-spun fiber observed when measured under a temperature rising condition from 50 ° C to 20 ° C / min is Tm1 (° C), and the heat of fusion at Tm1 (ΔHm1) (J / g) was measured. Similarly, the temperature of the endothermic peak of the resin used for melt spinning was Tm0 (° C.), the temperature of the endothermic peak of the fiber after heat treatment was Tm2 (° C.), and the heat of fusion at Tm2 (ΔHm2) (J / g) was measured. .
(2) Total fineness 100 m of fiber was removed with a measuring scale, the weight (g) was multiplied by 100, and 10 measurements per level were performed, and the average value was defined as fineness (dtex).
(3) Winding tension It measured using the tension meter (MODEL TTM-101) by Toray Engineering. In addition, a tension meter capable of measuring a full scale of 5 g and an accuracy of 0.01 g was used for the extremely low tension.
(4) Strength, elongation, elastic modulus, and strength fluctuation rate According to the method described in JIS L1013: 1999, using Tensilon UCT-100 manufactured by Orientec Co., Ltd. under the conditions of a sample length of 100 mm and a tensile speed of 50 mm / min. The measurement was performed 10 times per average, and the average value was defined as strength (cN), strength (cN / dtex), elongation (%), and elastic modulus (cN / dtex). Strength refers to the strength at the time of cutting in the measurement of tensile strength described in JIS L1013: 1999, and the rate of variation in strength is the greater of the absolute values of the maximum or minimum difference from the average value of 10 strengths. It calculated by the following formula using the value of one.
Strong fluctuation rate (%) = ((| maximum or minimum value−average value | / average value) × 100)
Reference example 1
In a 5 L reaction vessel equipped with a stirring blade and a distillation tube, 870 parts by weight of p-hydroxybenzoic acid, 327 parts by weight of 4,4′-dihydroxybiphenyl, 89 parts by weight of hydroquinone, 292 parts by weight of terephthalic acid, 157 parts by weight of isophthalic acid Then, 1433 parts by weight of acetic anhydride (1.08 equivalent of the total phenolic hydroxyl groups) was added, and the temperature was raised from room temperature to 145 ° C. over 30 minutes with stirring in a nitrogen gas atmosphere, followed by reaction at 145 ° C. for 2 hours. Then, it heated up to 330 degreeC in 4 hours.

  The polymerization temperature was maintained at 330 ° C., the pressure was reduced to 1.0 mmHg (133 Pa) in 1.5 hours, the reaction was continued for another 20 minutes, and the polycondensation was completed when the torque reached 15 kgcm. Next, the inside of the reaction vessel was pressurized to 1.0 kg / cm 2 (0.1 MPa), the polymer was discharged to a strand through a die having one circular discharge port having a diameter of 10 mm, and pelletized by a cutter.

  In this liquid crystalline resin (Reference Example 1), the structural unit (I) derived from p-hydroxybenzoic acid is 54 mol%, the structural unit (II) derived from 4,4′-dihydroxybiphenyl is 16 mol%, and the structure derived from hydroquinone. The unit (III) is 7 mol%, the structural unit (IV) derived from terephthalic acid is 15 mol%, the structural unit (V) derived from isophthalic acid is 8 mol%, and the melting point is 318 ° C. Using a tester, the melt viscosity measured at a temperature of 328 ° C. and a shear rate of 1000 / s was 16 Pa · s.

Reference example 2
In a 5 L reaction vessel equipped with a stirring blade and a distillation tube, 907 parts by weight of p-hydroxybenzoic acid, 457 parts by weight of 6-hydroxy-2-naphthoic acid, and 946 parts by weight of acetic anhydride (1. 03 molar equivalents) was charged into a reaction vessel equipped with a stirring blade and a distillation tube, and the temperature was raised from room temperature to 145 ° C. over 30 minutes while stirring in a nitrogen gas atmosphere, followed by reaction at 145 ° C. for 2 hours. Then, it heated up to 325 degreeC in 4 hours.

  The polymerization temperature was maintained at 325 ° C., the pressure was reduced to 1.0 mmHg (133 Pa) in 1.5 hours, the reaction was continued for another 20 minutes, and the polycondensation was completed when the torque reached 15 kgcm. Next, the inside of the reaction vessel was pressurized to 1.0 kg / cm 2 (0.1 MPa), the polymer was discharged to a strand through a die having one circular discharge port having a diameter of 10 mm, and pelletized by a cutter.

  This liquid crystalline resin (Reference Example 2) is composed of 73 mol% of a structural unit (I) derived from p-hydroxybenzoic acid and 27 mol% of a structural unit derived from 6-hydroxynaphthoic acid (other than (I) to (V)). The melting point was 283 ° C., and the melt viscosity measured at a temperature of 293 ° C. and a shear rate of 1000 / s using a Koka type flow tester was 32 Pa · s.

Example 1
After vacuum drying at 160 ° C. for 12 hours using the liquid crystalline polyester of Reference Example 1, it was melt extruded with a φ15 mm single-screw extruder (heater temperature 290 to 340 ° C.) manufactured by Osaka Seiki Co., Ltd. and measured with a gear pump. However, the polymer was supplied to the spinning pack. The spinning temperature from the extruder to the spinning pack at this time was 345 ° C. In the spinning pack, the polymer is filtered using a metal nonwoven fabric filter (WLF-10 manufactured by Watanabe Yoshikazu Co., Ltd.), and the discharge rate is 3.0 g / min from a die having five holes with a hole diameter of 0.13 mm and a land length of 0.26 mm ( The polymer was discharged at a rate of 0.6 g / min per single hole.

  The discharged polymer is allowed to pass through a 40 mm heat-retaining region, and then cooled and solidified from the outside of the yarn with an annular cooling air. Thereafter, an oil containing polydimethylsiloxane as a main component is applied, and all the 5 filaments are 1200 m / min. I took it to 1 godet roll. The spinning draft at this time is 32. After passing this through the second godet roll at the same speed, four of the five filaments are sucked with a suction gun, and the remaining one is brought into contact with the spindle traverse type pirn winder (winding package) through the dancer arm. It was wound up in the shape of a pan using a contact roll). During the winding time of about 100 minutes, yarn breakage did not occur and the yarn making property was good.

  This spun fiber had a fineness of 5.0 dtex, a strength of 5.9 cN / dtex, an elongation of 1.3%, and an elastic modulus of 511 cN / dtex, Tm1 of 298 ° C. and ΔHm1 of 2.9 J / g. The oil adhesion amount was 1.0% by weight.

  A winding machine (ET-68S speed-controlled winding manufactured by Kozu Seisakusho Co., Ltd.) that unwinds fibers from the spun fiber package in the longitudinal direction (perpendicular to the fiber circulation direction) and keeps the speed constant without using a speed-control roller. Machine) at 100 m / min. As the core material for rewinding, a stainless steel perforated bobbin wound with Kevlar felt (weight per unit: 280 g / m 2, thickness: 1.5 mm), the tension at the time of rewinding was 0.05 cN / dtex, and the winding amount was 2 It was 10,000 m, that is, 0.01 kg. Furthermore, the package form is a taper end winding with a taper angle of 20 °, the traverse width is always oscillated by modifying the taper width adjusting mechanism, no contact roll is used, and the traverse guide and fiber contact point is 5 mm from the fiber package. did. The number of winds was 5.1. The winding density of the package thus wound up was 0.08 g / cc.

  Using a closed oven, the temperature was raised from room temperature to 240 ° C. in about 30 minutes, held at 240 ° C. for 3 hours, then heated to 295 ° C. at 4 ° C./hour, and further at 295 ° C. for 15 hours. Solid state polymerization was carried out under the conditions maintained. The atmosphere was supplied with dehumidified nitrogen at a flow rate of 25 NL / min, and exhausted from the exhaust port so that the interior was not pressurized.

  The solid phase polymerization package thus obtained was attached to a feeding device that can be rotated by an inverter motor, and the fibers were unwound while being fed in the horizontal direction (fiber circumferential direction) at 500 m / min, but there was no yarn breakage and good unwinding property. The entire amount could be rewound.

  The fineness of the obtained liquid crystal polyester fiber is 5.0 dtex, strength 26.5 cN / dtex, strength fluctuation rate 8%, elongation 3.0%, elastic modulus 1002 cN / dtex, Tm2 is 332 ° C., ΔHm2 is 8 .4J / g and ΔHm2 / ΔHm1 were 2.9, and had high strength, elastic modulus and low strength fluctuation rate.

Example 2
Solid phase polymerized fibers were obtained in the same manner as in Example 1, except that the tension at the time of winding the melt-spun fiber was 0.03 cN / dtex and the winding density of the fiber package was 0.03 g / cc.

  The solid phase polymerization package obtained in this way is attached to a feeding device that can be rotated by an inverter motor, and when the fiber is unwound while being fed in the horizontal direction (fiber wrapping direction) at 500 m / min, the yarn breakage does not occur and the unwinding property is good. Yes, it was possible to rewind the entire amount.

  The fineness of the obtained liquid crystal polyester fiber is 5.0 dtex, strength 26.6 cN / dtex, strength fluctuation rate 8%, elongation 3.0%, elastic modulus 1012 cN / dtex, Tm2 is 332 ° C., ΔHm2 is 8 .4J / g and ΔHm2 / ΔHm1 were 2.9, and had high strength, elastic modulus and low strength fluctuation rate.

Example 3
A solid phase polymerized fiber was prepared in the same manner as in Example 1 except that the melt spinning fiber winding speed was 500 m / min, the winding tension was 0.12 cN / dtex, and the fiber package winding density was 0.25 g / cc. Obtained.

  The solid phase polymerization package thus obtained was unwound by the same method as in Example 1, and although yarn breakage occurred at the unwinding speed of 500 m / min, the unraveling was achieved by reducing the unwinding speed to 50 m / min. The inertia was good and the whole amount could be rolled up.

  The fineness of the obtained liquid crystal polyester fiber is 5.0 dtex, strength 22.8 cN / dtex, strength fluctuation rate 18%, elongation 2.6%, elastic modulus 987 cN / dtex, Tm2 is 332 ° C., ΔHm2 is 8 .4J / g and ΔHm2 / ΔHm1 were 2.9, and had high strength, elastic modulus and low strength fluctuation rate.

Comparative Example 1
A solid phase polymerized fiber was prepared in the same manner as in Example 1 except that the melt spinning fiber winding speed was 700 m / min, the winding tension was 0.14 cN / dtex, and the fiber package winding density was 0.33 g / cc. Obtained.

  The solid phase polymerization package thus obtained is attached to a feeding device that can be rotated by an inverter motor, and when the fiber is unwound while being fed in the horizontal direction (fiber circumferential direction) at 500 m / min, yarn breakage occurs, and even at 50 m / min. Thread breakage due to fusion occurs every few minutes. I couldn't solve the problem.

  The fineness of the obtained liquid crystal polyester fiber is 5.0 dtex, strength 16.8 cN / dtex, strength fluctuation rate 27%, elongation 1.9%, elastic modulus 842 cN / dtex, Tm2 is 332 ° C., ΔHm2 is 8 .4J / g and ΔHm2 / ΔHm1 were 2.9, the strength was low, and the strength fluctuation rate was low.

Comparative Example 2
Example 1 except that the melt-spun fiber was wound at a speed of 100 m / min, the tension at the time of winding was 0.11 cN / dtex, a fiber package was formed using a contact roller, and the winding density was 0.35 g / cc. Similarly, a solid-phase polymerized fiber was obtained.

  The solid phase polymerization package thus obtained is attached to a feeding device that can be rotated by an inverter motor, and when the fiber is unwound while being fed in the horizontal direction (fiber circumferential direction) at 500 m / min, yarn breakage occurs, and even at 50 m / min. Thread breakage due to fusion occurs every few minutes. I couldn't solve the problem.

  The fineness of the obtained liquid crystal polyester fiber is 5.0 dtex, strength 16.5 cN / dtex, strength fluctuation rate 30%, elongation 1.8%, elastic modulus 835 cN / dtex, Tm2 is 332 ° C., ΔHm2 is 8 .4J / g and ΔHm2 / ΔHm1 were 2.9, the strength was low, and the strength fluctuation rate was low.

Example 4
Using the liquid crystalline polyester of Reference Example 2, melt spinning was performed in the same manner as in Example 1 except that the spinning temperature was 325 ° C. and the spinning speed was 600 m / min. The spinning draft at this time is 32. The yarn-making property was good and it was possible to wind up for 100 minutes.

  The obtained spun fiber had a fineness of 10.0 dtex, a strength of 8.4 cN / dtex, an elongation of 1.8%, an elastic modulus of 501 cN / dtex, Tm1 of 286 ° C., and ΔHm1 of 3.2 J / g. The oil adhesion amount was 1.0% by weight.

  When this was wound up in the same manner as in Example 1, the winding tension was 0.05 cN / dtex, and a fiber package having a winding amount of 0.02 kg (20,000 m) and a winding density of 0.08 g / cc was obtained.

  This was subjected to solid state polymerization in the same manner as in Example 1 except that the final temperature reached 285 ° C.

  The solid phase polymerization package obtained in this way is attached to a feeding device that can be rotated by an inverter motor, and when the fiber is unwound while being fed in the horizontal direction (fiber wrapping direction) at 500 m / min, the yarn breakage does not occur and the unwinding property is good. Yes, it was possible to rewind the entire amount.

  The obtained liquid crystal polyester fiber has a fineness of 10.0 dtex, a strength of 21.1 cN / dtex, a strength fluctuation rate of 11%, an elongation of 3.1%, and an elastic modulus of 822 cN / dtex, Tm1 of 286 ° C. and ΔHm1 of 3 .2 J / g, Tm2 was 321 ° C., ΔHm2 was 9.4 J / g, and ΔHm2 / ΔHm1 was 2.9, and had high strength, elastic modulus, and low strength fluctuation rate.

Reference Example 5
A multi-piece that uses 24 nozzles with a discharge diameter of 12.0 g / min (0.5 g / min per single hole) from a die having 24 holes with a hole diameter of 0.13 mm and a land length of 0.26 mm. Melt spinning was performed in the same manner as in Example 1 except that the filament was taken up by a pair of godet rolls at 1200 m / min and wound up as it was. The spinning draft at this time is 38. During the winding time of about 100 minutes, yarn breakage did not occur and the yarn making property was good.

  This spun fiber had a fineness of 100.0 dtex, a strength of 5.5 cN / dtex, an elongation of 1.1%, and an elastic modulus of 464 cN / dtex, Tm1 of 298 ° C. and ΔHm1 of 2.9 J / g. The oil adhesion amount was 1.0% by weight.

  Using this spun fiber, the tension at the time of rewinding is 0.14 cN / dtex, the winding amount is 100,000 m, the taper angle is 5 ° taper end winding, and the traverse folding position is shortened once every 3 times and 2 mm at both ends. Rewinding was performed in the same manner as in Example 1 except that the end face was broken and the wind number was 2.3. The winding density of the package thus wound up was 0.28 g / cc.

  This was subjected to solid phase polymerization in the same manner as in Example 1. The solid phase polymerization package thus obtained was unwound by the same method as in Example 1, and although yarn breakage occurred at the unwinding speed of 500 m / min, the unraveling was achieved by reducing the unwinding speed to 100 m / min. The inertia was good and the whole amount could be rolled up.

  The fineness of the obtained liquid crystal polyester fiber is 100.0 dtex, strength 21.5 cN / dtex, strength variation 6%, elongation 2.8%, elastic modulus 860 cN / dtex, Tm2 is 335 ° C., ΔHm2 is 8 0.5 J / g and ΔHm2 / ΔHm1 were 2.9 and had high strength, elastic modulus and low strength fluctuation rate.

Comparative Example 3
Melt spinning was performed in the same manner as in Example 1. At this time, the take-up bobbin by melt spinning was made into a stainless steel boring bobbin and taken up directly on this. At this time, the winding tension was 0.18 cN / dtex, the winding amount was 0.01 kg (20,000 m), and the winding density of the package was 0.90 g / cc. The oil adhesion amount was 1.0% by weight. Without spinning the spinning package, solid phase polymerization was carried out in the same manner as in Example 1. An attempt was made to unravel this in the same manner as in Example 1, but the fusion of fibers was remarkably impossible to unravel. For this reason, fiber physical properties were evaluated using fibers obtained in a very small amount. Since the fineness after solid-phase polymerization could not be evaluated because the fibers could not be picked as a continuous yarn, the fineness of the spun fiber was used for calculation of strength and elastic modulus. The fineness was 5.0 dtex, the strength was 13.8 cN / dtex, the strength fluctuation rate was 32%, the elongation was 1.6%, and the elastic modulus was 783 cN / dtex, and the strength was low and the strength fluctuation rate was large.

Example 6
A base having 10 discharge holes with a hole diameter of 0.10 mm and L / D of 2.0 was used, the discharge rate was 2.5 g / min (0.25 g / min per single hole), and heat retention was 100 mm under the base. A melt spinning was performed in the same manner as in Example 1 except that a region was provided and the first godet roll speed was 1000 m / min. The spinning draft at this time is 43. During the winding time of about 100 minutes, yarn breakage did not occur and the yarn making property was good.

  Using the obtained spun fiber, the taper angle was 60 °, the wind number was 14.8, the rewinding speed was 50 m / min, and polydimethylsiloxane (SH200 manufactured by Toray Dow Corning) was 4.0% by weight, hydrophilic. -Based smectite (“Lucentite (registered trademark) SWN” manufactured by Co-op Chemical Co., Ltd.) is a 0.2% by weight water emulsion and is lubricated using a satin-finished stainless steel roll before the winder. Rewinding was performed in the same manner as in Example 1 except that the amount was 0.01 kg (40,000 m). The winding tension at this time was 0.13 cN / dtex, and the winding density was 0.26 g / cc. The oil adhesion amount was 7.8 wt%.

  This was subjected to solid phase polymerization in the same manner as in Example 1. The solid phase polymerization package thus obtained was unwound by the same method as in Example 1, and although yarn breakage occurred at the unwinding speed of 500 m / min, the unraveling was achieved by reducing the unwinding speed to 50 m / min. The inertia was good and the whole amount could be rolled up. However, there was a large amount of oil residue remaining on the guide in the middle of the unwinding process, and there was a concern that the process passability might be hindered when the winding amount further increased.

  The fineness of the obtained liquid crystal polyester fiber is 2.6 dtex, strength 22.4 cN / dtex, strength variation 14%, elongation 2.3%, elastic modulus 1084 cN / dtex, Tm2 is 336 ° C., ΔHm2 is 8 .6 J / g, ΔHm2 / ΔHm1 was 3.0, and had high strength, elastic modulus, and low strength fluctuation rate.

Example 7
Melt spinning was performed in the same manner as in Example 6 except that the discharge rate was 5.0 g / min (0.5 g / min per single hole). The spinning draft at this time is 22. During the winding time of about 200 minutes, yarn breakage did not occur and the yarn making property was good.

  Using the obtained spun fiber, the taper angle is 45 °, the wind number is 9.1, the rewinding speed is 200 m / min, and polydimethylsiloxane (SH200 manufactured by Toray Dow Corning) is 5.0% by weight of water. Rewinding was carried out in the same manner as in Example 1 except that the emulsion was used as an oil agent, oil was supplied using a satin finish stainless steel roll before the winder, and the winding amount was 0.05 kg (100,000 m). At this time, the winding tension was 0.10 cN / dtex and the winding density was 0.14 g / cc. The amount of oil adhered was 4.4 wt%.

  This was subjected to solid phase polymerization in the same manner as in Example 1. When the solid phase polymerization package thus obtained was unwound by the same method as in Example 1, yarn breakage occurred at the unwinding speed of 500 m / min, but the unwinding property was good at the unwinding speed of 200 m / min. It was possible to rewind the entire amount.

  The fineness of the obtained liquid crystal polyester fiber is 5.0 dtex, strength 25.8 cN / dtex, strength fluctuation rate 7%, elongation 2.7%, elastic modulus 1025 cN / dtex, Tm2 is 334 ° C., ΔHm2 is 8 .3 J / g and ΔHm2 / ΔHm1 were 2.9, and had high strength, elastic modulus, and low strength fluctuation rate.

Claims (2)

Melt spun denier than 1 dtex, the liquid crystal polyester melt spun fiber is less monofilament 100 dtex, the winding density of 0.01 g / cc or more, is formed on a bobbin as a fiber package of less than 0.30 g / cc, the package A method for producing a liquid crystal polyester fiber, characterized by heat-treating.   2. The method for producing a liquid crystal polyester fiber according to claim 1, wherein the fiber weight of the package is 0.01 kg or more and 10 kg or less.